Automatic transmission



March 13, 1945.

B. A. SWENNES AUTOMATIC TRANSMISSION Filed April 23, 1941 fizz/c Pn ar'"I .Bezy'anzin Qfjwennea Patented Mar. 13, 1 945 OFFICE j AUTOMATICTRANSMISSIQN Benjamin A. Swennes, Rockford, Ill assignor to, Borg-WarnerCorporatiomchicago, 111., a. corporatlon of Illinois Application April23, 1941, Serial No. 389,850"

' 4 Claims. (01. 74-1895) This invention relates to transmissions, andparticularly to a transmission utilizing a fluid device combined withgearing.

The inherent smoothness and shock-absorbing characteristics of fluiddevices such as hy.- draulic couplings of the Fottinger type makes thesedevices desirable for use in automobile transmissions. A hydrauliccoupling, however, does not multiply torque, and accordingly, must beused with gearing in order to obtainthe high torque ratios necessary toprovide an automobile with a suitable amount of acceleration. Thiscreates shifting problems, particularly where positive clutches areused, since a hydraulic coupling transmits torque as a function of thespeed of the driving element thereof, and if the driving element iscontinuously'rotated as it would be when directly con'nected'with anautomobile engine, a certain amount of torque is always transmitted tothe positive clutch, thereby ren-- dering shifting either difficult orimpossible. This is particularly truewhere a positive clutch is used toeffect a shift from neutral into either forward or reverse. When theshifting is to be done automatically in accordance with present trends,the problem becomes even more complex. e

The objects of this invention isto provide an automatic transmissionemploying a fluid device combined with gearing, wherein under ordinarycircumstances no shifting of positive toothed elements isrequired-between neutral," forward and reverse, and which neverthelessdoes not require any complicated controls. p

Another object of this invention is to provide a simple, inexpensivetwo-speed automatic transmission suitable for use in low-priced cars.Another object of this invention is to provide a two-speed automatictransmission with an intermediate manually operated speed available foruse in emergencies.

These and other objects and features of the invention will becomeapparent from the following description when taken together with theaccompanying drawing, in which:

7 Fi l is a fragmentary side elevation partly in section of oneembodiment ofthe invention; Fig. 2 is a schematic line drawing. showingthe principal torque transmitting elements of the transmission inFig l;

Fig. 3 is a fragmentary section taken along line 33 of Fig. l.

-Referring now to the drawing, and particularly to Figs. 1 and 2, thetransmission is comprised of a drive shaft 10, a driven shaft I], ahydraulic coupling l2, planetary gearing I3, an

overrunning clutch 22', an intermediate shaft l4 connecting-the clutch22 and gearing l3, an auto tionbetween gearing l3 and drive shaft I0,and

a manually controlled clutch l6 for locking gearing l3 with couplin l2around overrunning clutch 22. Secured toshaft'lll isa fly-wheel housingll which-forms a container for hydraulic coupling l2. Saidcoupli'ng l2hasan impeller member I 8 likewise securedto'drive shaft l0 and a.runner is adapted to be driven by impeller l8 through the "mediumofoilor other fluidsubstantiallyfilling housing l1. Runner I9 ismounted on asplined hub 20, which is splined to a sleeve 2|.

Theforwardend(to-theleft in Fig. 1) of sleeve 2| is enlarged toaccommodate one-way clutch 22, which is of'the roller-and-cam type, and

a groove 29in collar .25. A yoke 30 cooperates with collar '28 to movesaid collar in an axial direction. Yoke- 30 iscontrolled by means of aspring 89 and a solenoid 3|, which in turn is supplied with electricalenergy from a battery 32 or other source of electromotive force,througha switch 33 operated by a button 34. Said switch is of such acharacter that whenwbutton 34 is depressed and then released, a changeis effected in the electrical circuit which obtains until said button 34is again depressed and released. Spring 83 normally biases yoke 30 to.the left (Fig. l) to engage clutch l6; i Planetary gear set I3 iscomprised of a sun gear 35 formed on theiend of shaft 14, a sun gear 36formed on the adjacent end of driven shaft H, a third sun gear:3l-formed on a sleeve 16, which surrounds shaft l4, and one or more setsofclu'ster gears 38, 39 and 40, meshing respectivelywith sun gears 35,3B, 31. Said cluster gears are "m'ounted on a'carrier 4| which iscoaxial with'shafts I4 and H. Said carrier 4| is connected to a flangedhub 43 by means of a one-way clutch 44. which permits rotation betweencarrier 4| and hub 43 when carrier 4! tends to rotate ahead of hub 43.Flanged hub 43 is latter under these circumstances acting as a onewaybrake. If the reaction is in the opposite direction, the one-way brakereleasesand: carrier 4| will rotate even though brake 46 is stillapplied. A second brake, operative inboth directions, is also providedfor carrier 41. This brake is comprised of a drum I3 rigidly secured tocarrier 4| and a brake band "which ismanually the car gains momentum. Atsome predetermined speed said pawls 18 will move radially outwardly tocontact drum 85. At this time, drum 85 is rotating faster than pawls I8and the latter, therefore, will not engage slots 86, but will ratchetover them. This will continue as long as drive shaft H) is driven by theengine, that is, as long as torque is impressed upon drive shaft m whichis greater than: the load on driven shaft 'Thus, this condition mayobtain over a relatively large range of speeds, and direct drive may bedelayed or accelerated at the will of the operator.

When the operator wishes to shift into direct drive, he simply releasesthe accelerator to decelerate theengine, whereupon drum 85 will proceedto slow down with respect to 11, and eventually will. reach a point ofsynchronism therewith. If

controlled, and which cooperates with drum l3 to arrest the latter. Thefunction of this'brake will be described hereinaiten.

Clutch |5iscompri$ed of3-a carrier Hill; which are mountedoneormorezradially movable pawls l8. Carrier'll alsosupportsa brake; drum 19,which cooperates with" a double-wrapbrakeband 51. Housing I12 isattached to: a-toothed: hub member 8|, which iistconnectedl throughinterfitting teeth 82 toa cylindrical stamping-83= surrounding shaft|4'. Sa'idzstamping 83:is.connected througha-vibrationabsorbing:device84 toa drum 85 having slots 83. in: axial;alignment with radially movable pawls 18'... The-.pawls-are normallyheld'in retracted position by means of a. biasing sprlnglll. A slot 1'2instamping 83 allows pin=2l to pass through thestamping to groove-29.

The operation of the. transmission is as follows:

Assuming that" the engine. isr rotating and that drive shaft In is,therefore, likewise rotating, housing ||,"impeller' |8Land clutch. drum85-. will be rotated simultaneously with drive shaft l0, since they areall connected together; These elements, therefore, rotate whether theengine is developing driving torque"orisimerelyiidling. If it" isdesired to test. or warm up the engine. without transmitting any torqueto: driven shaft H brake bands 46, 51 and H are released to conditionthe transmissionfor: neutral. Any driving torque-transmittedthroughncoupling I2: to sun gear is thereby. dissipated-by the rotationof carrier 4| about sun gear 38 'ondriven-.shaft Sun gear 31 a'nd itsassociated carrier I'land pawls l8 will likewise be; rotated, but due tothe planet'ating action'. ofgear" 40-; ,the actual. speed of sun gear"31 will not. be" sufflci'ent tocause.- pawls I8 to move outwardlytovengage the clutcln Assuming that-the driver wishes to put the car inmotion in "a forward direction, brake band-46 will be applied to arrestthe-rotation of him 43. Since there is a. load on driven shaft. H, thetorque transmitted through coupling: l2, overrunning clutch 22 and sungear: 35 will cause the carrier 4| to lean. on. one-way brake 44,. whichin turn reactslagainstchub 43'; and brake band 56. a The net:result,1there'fore;; is to arrest the a rotation of carrier 41':sofithat-it becomes a countershait, and driven shaft t will berotated.at. a reduced speedthrough sun. gear. .35, .planet gears 38 and 39 andsun 'geaniifi; This-drivewillbe a 100 per cent. fluidrdrivetthat'isitosay, all the engine torque 'WiH' be transmitted; through coupling l2."Simultaneously with. the. rotation of planet gear 33, planet-gear40,-will-1ikewise be rotated, which-in turn wilhdrive sungear. 3?! andits associated pawls 18 atran increasing speed as associated drivenshaft H.

at thispoint a pawl is in line with a slot, engagement will occur, butif the two are not in alignment, the continued slowing down of drum 86will cause; a relative reversalin the direction of rotation of drum withrespect. to pawl 18, so

that when the next slot. 86 drifts past pawl 18, the latter will engagethe slot due-to theshape of the endof the pawl. The resumption of thedrive in drive shaft 10 will then provide adrive between shaft' l0 andsun gear. 3'1. Clutch |.5 will remain engaged until. the speed of sungear 31 falls below a predetermined speed, whereupon the release ofclutch l5 isautomatically efiected by springs 81. I

Thus, sun gear 31. will be driven at engine speed, and sun gear 35 willtend to rotate at some speed. greater than engine speed because of thedifierence in the: size of planet gears 38 and 40. It will be assumedfor the present that lock-out clutch |6 has been operated to by-passoverrunning. clutch 22 and that the tendency to rotate gear 35 fasterthan the engine. will be prevented. by fluid coupling I2, which. atthese speeds is operating at substantially one-to-one ratio. With bothsun gears rotating at approximately the same speed, the planetary gearset will be locked up and driven shaft II will rotate at substantiallyengine speed.

To obtain reverse, brake band 46 is released and brake. band 5'! isapplied. The. drive is again through coupling l2 and by-pass clutch Hito sun gear 35, butsun gear 31 is locked to housing 4.-|:' through brakeband 57. Due to thedifierence in. size of sun gears. 35and. 3'1, carrier4| will be driven; in a reverse direction with respectto sun gear 35,and will carry with,it.sun gear 36 and its This results in a reverserotation of driven shaft. H at a reduced speed.

It'will be apparent. thus far that the transmission just described canbe operated as an automatic two-speed transmission. In some cases,however, two speeds are not. sufficient, and it is desirable to providean intermediate speed. corresponding to second speed in. the standardtransmission. This is accomplished by the means now tobe described.

It will benoted that when. the. transmission is operated asatwo-speedtransmission, jaw clutch |6is engaged to. make overrunningclutch 22 ineffeetive. This prevents sungear 35 from rotating fasterthan drive-shaft. 1,, and as a. consequence, the planetary gear. set.is. locked up in one-to-one drive when clutch I5 is engaged. To securean. intermediate second speed,.itis necessary to. release clutch Hi. topermit sun gear 35 to rotate. freely. Under these conditions theengagement of automatic clutch l5 transfers the drivefrom sun gear 35'tothe smaller sun gear 31, the reaction in carrier 4| remaining in areverse direction, and a higher speed ratio drive than results.- e I eThe release of clutch 6 to secure second speed drive is effected bydepressing button 34 to break the circuit through solenoid 3|-. spring89 to disengage clutch l6 by suitably operating yoke 30 and slidablecollar 28. I Said collar 28 is, of course, rotated with sleeve 83 byreason of the pin.2'| which passes throughslot 12 in sleeve '83. Button34 may be depressed while the transmission is in neutral to cause secondspeed to become effective immediately after the" released and sun gear35 is driven initially froni coupling through overrunning clutch 22, the

transmission having been previously conditioned for low speed byoperating brake 48 to arrest carrier 4| through one-way brake 44 tocausefit to act as a countershaft. Sun'gear 31 is likewise rotated, andwhen the speed 'for which clutch I5 is set is reached, said clutch willengage so that the sun gear 31 is driven at engine speed. Due to theoverrunning clutch 22, the resulting high speed rotation ofsun gear35'has noeffect upon the drive, and planet gear 39 being smaller thanplanet gear 40, an intermediate speed ratio will be effected betweendrive shaft I 0 and driven shaft II. This drive is a purely mechanicaldrive and is independent of fluid coupling 2.

The transmission will remain in second speed until the driver againdepresses foot button 34 to operate solenoid 3|. This will cause yoke 30and its associated elements to be biased to the left, that is, towardthe engaged position of clutch I6. If, at this instant the clutch teeth'23 and 26 are in alignment, the clutch will en? gage immediately,thereby connecting runner l9 around overrunning clutch 22 tointermediateshaft l4 and sun gear 35. Sun gear 35 will then be rotated atsubstantially the same speed as gear 31 and the gear set will beconditioned for direct drive. If, however, clutch teeth 23 and 2 are notin alignment, but are butt-ended, the operator may release theaccelerator so as to slow down the engine, and the momentum of the carwill then drive sun gear 36 and planetgears 39, 38 and 40. Clutch l5having previously been engaged will remain engaged, thereby causing sungear 3'! to rotate 'at the same speed as drive shaft l0. With the drivereversed, how-.

ever, so that sun gear 36 is a driving member and fore coast in directdrive. This means that there will be no relative rotation between teeth23 and 26, and the problem of synchronizing them prior to engagementiseliminated. Upon the next torque reversal, that is, when theaccelerator is again depressed to cause drive shaft II! to rotate-fasterthan driven shaft H, the reaction of the load on gear 36 will tend toagain rotate gear 35 faster than runner l9, but due to the bias on teeth26, this rotation will last for This causes only a fraction of a toothand will cease when clutch teeth 23 and 26 are aligned and becomeengaged. The resulting drive will then be a di rect drive.

Assuming'now thatthe transmission is in direct and that button 34 hasbeen depressed to effect a down shift, a releasing bias will beimpressed upon clutch l6. If this bias is greater than the torque loadon the clutch, thelatter will release and sun gear 35 will spin freelyahead of runner I9. Carrier 4| will then assume the resulting backwardreaction and transfer it through one-way brake 44 to brake band 46. If,

however, the bias is not sufficient, the engine may be slowed down, asfor example by releas ing the accelerator, to decrease the torque, andduring the momentary torque reversal which ensues, the load onclutch IEwill be relieved sufficiently to permit teeth 26 to be disengaged. Upona resumption of the drive, sun gear 35 will be freed because ofoverrunning clutch 22 and the transmission will be in second speed. Theshift back to direct will be made as described above.

In direct drive, only a fraction ofv the torque is transmitted throughthe coupling, the re+ m'aincler being transmitted through clutch I5;which-is a mechanical drive. Thus, in low speed the benefit of thesmooth start which is inherent in a 'fiuid drive, and in direct drive,the torque is divided so that the couplingtransmits only, a fraction ofthe total torque, which results: in maximum efliciency at the speeds atwhich-the transmission will-be operated the greaterl portion of thetime. In second speed the drive is apure lymechanical drive, whicheliminates excessive slipping of the coupling under heavy loadconditions, suchas long inclines, and prevents undue heating of thecoupling. Where along and steep downgrade is encounteredso as to makedesirable the use of the engine as a brake, the second brake. mentionedis provided for carrier 4|. This is necessary be- -cause one-way brake44 will release underv these conditions, and the transmission will becoasting suitable brake band 14, which is adapted to em operate withdrum 13 to arrest'therotation thereof. When it is desired to. coast insecond against the engine, brake 74 is applied to arrest the rotation ofcarrier 4| and clutch IE will be released to permit shaft M to overrunrunner 19 through overrunning clutch 22. When power is again applied todrive driven shaft II, the transmission will be in second speed, andwill remain so conditioned until brake band 14 is released and clutch 6is, subsequently reengaged.

It will be noted that with the pawl type of clutch the diameter of thehousing at the clutch is small, and the transmission as a whole is shortis possible to apply brake 4B of Fig. 1 when the and compact.

No controls are shown here for the various brake bands, it being assumedthat suitable controls can be designed to meet the particularrequirements of the manufacturer or user. It is contemplated, however,that the controls be manually operated so that the brakes may be appliedwhether or not the engine or car is in operation. With manually operatedcontrols it engine is not running, and thereby crank the engine bypushing the car. For this type of cranking, jaw clutch It mustbeoperated so as to drive the: runner of the coupling from driven shaftII, and thereby drive the impeller audits associated crank shaft I0.This operation will be efiected by means of spring 89 in Fig. 1.

It is understood that the foregoing description is merely illustrativeof one embodiment of this invention and that the scope of the claims isnot to'be limited thereto, but is to be determined by the appendedclaims.

I claim:

1. A transmission comprising a drive shaft, a driven. shaft, a gear onsaid driven shaft, an in termediate shaft, a; gear on said intermediateshaft, a hydraulic coupling having an impeller connected to the driveshaft and a runner, a sleeve surrounding the intermediate shaft andconnected to rotate with the runner, an overrunning clutch connectingthe sleeve to the intermediate shaft in a manner permitting the shaft torotate ahead of the sleeve, a positive clutch for connecting the sleeveand intermediateshaft for two-way drive around the overrunning clutch, agear concentric with the intermediate shaft, a positive clutchcomprising a slotted drum, a slotted cylindrical element connected torotate with the drive shaft andtransmitting the drive to the drum and aradially movable cen trifugally controlled pawl in axial alignment withthe slots in the drum; a sleeve connected to rotate with the concentricgear, a carrier for the pawl driven by the sleeve, an axially shiftablecollar surrounding the cylindrical element, a

connection between the collar and positive clutch to control theoperation of the positive clutch,

manually controlled means for shifting the collar, planet gearscooperating with each of the gears, a carrier for the planet gears,one-way brake means for arresting the rotation of the carrier for lowspeed drive, two-way brake means for driving the drive shaft from thedriven shaft assume.

shaft, said brake and said last named means cooperating to provide a lowspeed drive through the transmission, coupling means' including aslotted rotatable element and a radially slid/a.- ble pawl adapted toengage the slotted element, said coupling means being connected inseries with said other sun gear and adapted to complete a higher speedratio train through the transmission, and a one-way coupling deviceoperative to establish said high speed ratio when the torque isreversed.

3.- In a variable speed transmission, the combination of drive anddriven shafts, planetary gearing including at least a pair of sun gears,a planet gear in mesh with each of the sun gears and a carrier for theplanet gears, said driven shaft being connected with one of the elementsof said gearing, a roller and cam typeone-way brakefor one ofv theelements of the planetary gearing and means for driving one of said sungears from said drive shaft, said brake and said last named meanscooperating to provide a low speeddrive throughthe transmission and saidbrake being adapted to release upon a reversal of torque through thetransmission, coupling means including a slotted rotatable element and aradially slidable pawl adapted to engage the slotted element, saidcoupling means being con- .nected in series with the'other sun gear andin a geared ratio, and two-way brake means asadapted to complete ahigher speed ratio train through the transmission, and a one-waycoupling device automatically operable upon a release of the one-waybrake to establish said higher speed ratio when the torque is reversed.

4.iA transmission comprising a drive shaft, a driven'shaft, and changespeed mechanism connectable between said shafts including means fordriving the driven shaft at first, second and thirdspeed ratios, saidsecond speed means comprising a speed controlled positive clutch elementrotatable in timed relation with the driven shaft and a cooperatingclutch element associated with the drive shaft, said speed controlledelement being dependent upon substantial synchronization with thecooperating element before effecting engagement'therewith, said speedcontrolled clutch element comprising a radially movable pawl, and saidcooperating clutch element comprising a drum having slots in axialalignment with the pawl.

BENJAMIN A. SWENNES.

